Computer systems have a firmware Basic Input/Output System (“BIOS”) to initialize the hardware and interface the hardware with the Operating System software. Although Operating Systems utilize device drivers for standard devices as the interface to the hardware, certain hardware devices of the computer such as the north bridge devices that are discussed below are not interfaced to the software through device drivers. The north bridge is a chipset of hardware that interfaces one or more processing units and system memory on one side and the peripheral subsystem on the other. This hardware is non-standard equipment of the computer system and does not follow industry specifications of such devices. The BIOS continues to handle the interfacing of these devices to the operating system.
To provide this interface to these devices not otherwise handled by a device driver, the BIOS conventionally contains a DSDT that provides at least some of the descriptions necessary to interface these devices to the software. The DSDT applies to a particular configuration of north bridge devices for the computer system, and the DSDT is a binary file that is generated during manufacturing of the BIOS for a known computer system configuration. Upon boot-up of the computer system, a pointer to the DSDT is included in a root system description table (“RSDT), which the operating system references to find the DSDT and learn the configuration of the system.
For certain computer systems such as high capacity computer servers, the north bridge may have many configurations which can be changed by a user or by a malfunction of a component of the north bridge device. For example, the Intel® i870 north bridge chipset provides up to four Scalability Node Controllers (“SNC”) which are the main components of the North Bridge, with each SNC linked to two Scalability Port Switches (“SPS”) where each SPS also links up to two Server Input/Output Hubs (“SIOH”). Each SNC can support up to four microprocessors and part of system memory.
Several examples of configurations for this north bridge are possible. In one example, a given system may use both SPS, all four associated SNC, and both SIOH. In another example, only a single SNC per SPS may be provided. In yet another example, the SPS may fail such that a single SNC is hardwired directly to the SIOH corresponding to the failed SPS. As an additional example, a user may choose to partition through the operating system the north bridge into two separate systems where each system has one SPS, one corresponding SIOH, and at least one corresponding SNC. Also, the number of SPS, SNC, and SIOH that is visible to the Operating System may be changed by the user adding or removing the hardware devices from the computer system.
Thus, the device configuration of the computer system may change after the computer system has reached the consumer. Because the BIOS conventionally has only one DSDT which provides the system description for one configuration of the computer system, a subsequent change to the computer system's configuration will result in the DSDT no longer being an accurate system description. The computer system may then function incorrectly due to the inaccurate DSDT. Where a particular unconventional configuration is requested by a customer, the manufacturer must then create a new DSDT for the BIOS to work with the requested configuration and this can be a difficult and time-consuming process.